1 files changed, 122 insertions, 230 deletions

diff --git a/net/dccp/ccids/lib/loss_interval.c b/net/dccp/ccids/lib/loss_interval.c
index d26b88dbbb4..849e181e698 100644
--- a/net/dccp/ccids/lib/loss_interval.c
+++ b/net/dccp/ccids/lib/loss_interval.c
@@ -1,6 +1,7 @@
 /*
  *  net/dccp/ccids/lib/loss_interval.c
  *
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
  *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
  *  Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
@@ -10,285 +11,176 @@
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  */
-
-#include <linux/module.h>
 #include <net/sock.h>
-#include "../../dccp.h"
-#include "loss_interval.h"
-#include "packet_history.h"
 #include "tfrc.h"
 
-#define DCCP_LI_HIST_IVAL_F_LENGTH  8
-
-struct dccp_li_hist_entry {
-	struct list_head dccplih_node;
-	u64		 dccplih_seqno:48,
-			 dccplih_win_count:4;
-	u32		 dccplih_interval;
-};
+static struct kmem_cache  *tfrc_lh_slab  __read_mostly;
+/* Loss Interval weights from [RFC 3448, 5.4], scaled by 10 */
+static const int tfrc_lh_weights[NINTERVAL] = { 10, 10, 10, 10, 8, 6, 4, 2 };
 
-static struct kmem_cache *dccp_li_cachep __read_mostly;
-
-static inline struct dccp_li_hist_entry *dccp_li_hist_entry_new(const gfp_t prio)
+/* implements LIFO semantics on the array */
+static inline u8 LIH_INDEX(const u8 ctr)
 {
-	return kmem_cache_alloc(dccp_li_cachep, prio);
+	return (LIH_SIZE - 1 - (ctr % LIH_SIZE));
 }
 
-static inline void dccp_li_hist_entry_delete(struct dccp_li_hist_entry *entry)
+/* the `counter' index always points at the next entry to be populated */
+static inline struct tfrc_loss_interval *tfrc_lh_peek(struct tfrc_loss_hist *lh)
 {
-	if (entry != NULL)
-		kmem_cache_free(dccp_li_cachep, entry);
+	return lh->counter ? lh->ring[LIH_INDEX(lh->counter - 1)] : NULL;
 }
 
-void dccp_li_hist_purge(struct list_head *list)
+/* given i with 0 <= i <= k, return I_i as per the rfc3448bis notation */
+static inline u32 tfrc_lh_get_interval(struct tfrc_loss_hist *lh, const u8 i)
 {
-	struct dccp_li_hist_entry *entry, *next;
-
-	list_for_each_entry_safe(entry, next, list, dccplih_node) {
-		list_del_init(&entry->dccplih_node);
-		kmem_cache_free(dccp_li_cachep, entry);
-	}
+	BUG_ON(i >= lh->counter);
+	return lh->ring[LIH_INDEX(lh->counter - i - 1)]->li_length;
 }
 
-EXPORT_SYMBOL_GPL(dccp_li_hist_purge);
-
-/* Weights used to calculate loss event rate */
 /*
- * These are integers as per section 8 of RFC3448. We can then divide by 4 *
- * when we use it.
+ *	On-demand allocation and de-allocation of entries
  */
-static const int dccp_li_hist_w[DCCP_LI_HIST_IVAL_F_LENGTH] = {
-	4, 4, 4, 4, 3, 2, 1, 1,
-};
-
-u32 dccp_li_hist_calc_i_mean(struct list_head *list)
+static struct tfrc_loss_interval *tfrc_lh_demand_next(struct tfrc_loss_hist *lh)
 {
-	struct dccp_li_hist_entry *li_entry, *li_next;
-	int i = 0;
-	u32 i_tot;
-	u32 i_tot0 = 0;
-	u32 i_tot1 = 0;
-	u32 w_tot  = 0;
-
-	list_for_each_entry_safe(li_entry, li_next, list, dccplih_node) {
-		if (li_entry->dccplih_interval != ~0U) {
-			i_tot0 += li_entry->dccplih_interval * dccp_li_hist_w[i];
-			w_tot  += dccp_li_hist_w[i];
-			if (i != 0)
-				i_tot1 += li_entry->dccplih_interval * dccp_li_hist_w[i - 1];
-		}
-
-
-		if (++i > DCCP_LI_HIST_IVAL_F_LENGTH)
-			break;
-	}
-
-	if (i != DCCP_LI_HIST_IVAL_F_LENGTH)
-		return 0;
-
-	i_tot = max(i_tot0, i_tot1);
-
-	if (!w_tot) {
-		DCCP_WARN("w_tot = 0\n");
-		return 1;
-	}
-
-	return i_tot / w_tot;
+	if (lh->ring[LIH_INDEX(lh->counter)] == NULL)
+		lh->ring[LIH_INDEX(lh->counter)] = kmem_cache_alloc(tfrc_lh_slab,
+								    GFP_ATOMIC);
+	return lh->ring[LIH_INDEX(lh->counter)];
 }
 
-EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);
-
-static int dccp_li_hist_interval_new(struct list_head *list,
-				     const u64 seq_loss, const u8 win_loss)
+void tfrc_lh_cleanup(struct tfrc_loss_hist *lh)
 {
-	struct dccp_li_hist_entry *entry;
-	int i;
-
-	for (i = 0; i < DCCP_LI_HIST_IVAL_F_LENGTH; i++) {
-		entry = dccp_li_hist_entry_new(GFP_ATOMIC);
-		if (entry == NULL) {
-			dccp_li_hist_purge(list);
-			DCCP_BUG("loss interval list entry is NULL");
-			return 0;
+	if (!tfrc_lh_is_initialised(lh))
+		return;
+
+	for (lh->counter = 0; lh->counter < LIH_SIZE; lh->counter++)
+		if (lh->ring[LIH_INDEX(lh->counter)] != NULL) {
+			kmem_cache_free(tfrc_lh_slab,
+					lh->ring[LIH_INDEX(lh->counter)]);
+			lh->ring[LIH_INDEX(lh->counter)] = NULL;
 		}
-		entry->dccplih_interval = ~0;
-		list_add(&entry->dccplih_node, list);
-	}
-
-	entry->dccplih_seqno     = seq_loss;
-	entry->dccplih_win_count = win_loss;
-	return 1;
 }
+EXPORT_SYMBOL_GPL(tfrc_lh_cleanup);
 
-/* calculate first loss interval
- *
- * returns estimated loss interval in usecs */
-static u32 dccp_li_calc_first_li(struct sock *sk,
-				 struct list_head *hist_list,
-				 ktime_t last_feedback,
-				 u16 s, u32 bytes_recv,
-				 u32 previous_x_recv)
+static void tfrc_lh_calc_i_mean(struct tfrc_loss_hist *lh)
 {
-	struct dccp_rx_hist_entry *entry, *next, *tail = NULL;
-	u32 x_recv, p;
-	suseconds_t rtt, delta;
-	ktime_t tstamp = ktime_set(0, 0);
-	int interval = 0;
-	int win_count = 0;
-	int step = 0;
-	u64 fval;
+	u32 i_i, i_tot0 = 0, i_tot1 = 0, w_tot = 0;
+	int i, k = tfrc_lh_length(lh) - 1; /* k is as in rfc3448bis, 5.4 */
 
-	list_for_each_entry_safe(entry, next, hist_list, dccphrx_node) {
-		if (dccp_rx_hist_entry_data_packet(entry)) {
-			tail = entry;
+	for (i=0; i <= k; i++) {
+		i_i = tfrc_lh_get_interval(lh, i);
 
-			switch (step) {
-			case 0:
-				tstamp	  = entry->dccphrx_tstamp;
-				win_count = entry->dccphrx_ccval;
-				step = 1;
-				break;
-			case 1:
-				interval = win_count - entry->dccphrx_ccval;
-				if (interval < 0)
-					interval += TFRC_WIN_COUNT_LIMIT;
-				if (interval > 4)
-					goto found;
-				break;
-			}
+		if (i < k) {
+			i_tot0 += i_i * tfrc_lh_weights[i];
+			w_tot  += tfrc_lh_weights[i];
 		}
+		if (i > 0)
+			i_tot1 += i_i * tfrc_lh_weights[i-1];
 	}
 
-	if (unlikely(step == 0)) {
-		DCCP_WARN("%s(%p), packet history has no data packets!\n",
-			  dccp_role(sk), sk);
-		return ~0;
-	}
-
-	if (unlikely(interval == 0)) {
-		DCCP_WARN("%s(%p), Could not find a win_count interval > 0. "
-			  "Defaulting to 1\n", dccp_role(sk), sk);
-		interval = 1;
-	}
-found:
-	if (!tail) {
-		DCCP_CRIT("tail is null\n");
-		return ~0;
-	}
-
-	delta = ktime_us_delta(tstamp, tail->dccphrx_tstamp);
-	DCCP_BUG_ON(delta < 0);
+	BUG_ON(w_tot == 0);
+	lh->i_mean = max(i_tot0, i_tot1) / w_tot;
+}
 
-	rtt = delta * 4 / interval;
-	dccp_pr_debug("%s(%p), approximated RTT to %dus\n",
-		      dccp_role(sk), sk, (int)rtt);
+/**
+ * tfrc_lh_update_i_mean  -  Update the `open' loss interval I_0
+ * For recomputing p: returns `true' if p > p_prev  <=>  1/p < 1/p_prev
+ */
+u8 tfrc_lh_update_i_mean(struct tfrc_loss_hist *lh, struct sk_buff *skb)
+{
+	struct tfrc_loss_interval *cur = tfrc_lh_peek(lh);
+	u32 old_i_mean = lh->i_mean;
+	s64 length;
 
-	/*
-	 * Determine the length of the first loss interval via inverse lookup.
-	 * Assume that X_recv can be computed by the throughput equation
-	 *		    s
-	 *	X_recv = --------
-	 *		 R * fval
-	 * Find some p such that f(p) = fval; return 1/p [RFC 3448, 6.3.1].
-	 */
-	if (rtt == 0) {			/* would result in divide-by-zero */
-		DCCP_WARN("RTT==0\n");
-		return ~0;
-	}
+	if (cur == NULL)			/* not initialised */
+		return 0;
 
-	delta = ktime_us_delta(ktime_get_real(), last_feedback);
-	DCCP_BUG_ON(delta <= 0);
+	length = dccp_delta_seqno(cur->li_seqno, DCCP_SKB_CB(skb)->dccpd_seq);
 
-	x_recv = scaled_div32(bytes_recv, delta);
-	if (x_recv == 0) {		/* would also trigger divide-by-zero */
-		DCCP_WARN("X_recv==0\n");
-		if (previous_x_recv == 0) {
-			DCCP_BUG("stored value of X_recv is zero");
-			return ~0;
-		}
-		x_recv = previous_x_recv;
-	}
+	if (length - cur->li_length <= 0)	/* duplicate or reordered */
+		return 0;
 
-	fval = scaled_div(s, rtt);
-	fval = scaled_div32(fval, x_recv);
-	p = tfrc_calc_x_reverse_lookup(fval);
+	if (SUB16(dccp_hdr(skb)->dccph_ccval, cur->li_ccval) > 4)
+		/*
+		 * Implements RFC 4342, 10.2:
+		 * If a packet S (skb) exists whose seqno comes `after' the one
+		 * starting the current loss interval (cur) and if the modulo-16
+		 * distance from C(cur) to C(S) is greater than 4, consider all
+		 * subsequent packets as belonging to a new loss interval. This
+		 * test is necessary since CCVal may wrap between intervals.
+		 */
+		cur->li_is_closed = 1;
+
+	if (tfrc_lh_length(lh) == 1)		/* due to RFC 3448, 6.3.1 */
+		return 0;
 
-	dccp_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
-		      "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
+	cur->li_length = length;
+	tfrc_lh_calc_i_mean(lh);
 
-	if (p == 0)
-		return ~0;
-	else
-		return 1000000 / p;
+	return (lh->i_mean < old_i_mean);
 }
+EXPORT_SYMBOL_GPL(tfrc_lh_update_i_mean);
 
-void dccp_li_update_li(struct sock *sk,
-		       struct list_head *li_hist_list,
-		       struct list_head *hist_list,
-		       ktime_t last_feedback, u16 s, u32 bytes_recv,
-		       u32 previous_x_recv, u64 seq_loss, u8 win_loss)
+/* Determine if `new_loss' does begin a new loss interval [RFC 4342, 10.2] */
+static inline u8 tfrc_lh_is_new_loss(struct tfrc_loss_interval *cur,
+				     struct tfrc_rx_hist_entry *new_loss)
 {
-	struct dccp_li_hist_entry *head;
-	u64 seq_temp;
-
-	if (list_empty(li_hist_list)) {
-		if (!dccp_li_hist_interval_new(li_hist_list, seq_loss,
-					       win_loss))
-			return;
-
-		head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
-				  dccplih_node);
-		head->dccplih_interval = dccp_li_calc_first_li(sk, hist_list,
-							       last_feedback,
-							       s, bytes_recv,
-							       previous_x_recv);
-	} else {
-		struct dccp_li_hist_entry *entry;
-		struct list_head *tail;
+	return	dccp_delta_seqno(cur->li_seqno, new_loss->tfrchrx_seqno) > 0 &&
+		(cur->li_is_closed || SUB16(new_loss->tfrchrx_ccval, cur->li_ccval) > 4);
+}
 
-		head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
-				  dccplih_node);
-		/* FIXME win count check removed as was wrong */
-		/* should make this check with receive history */
-		/* and compare there as per section 10.2 of RFC4342 */
+/** tfrc_lh_interval_add  -  Insert new record into the Loss Interval database
+ * @lh:		   Loss Interval database
+ * @rh:		   Receive history containing a fresh loss event
+ * @calc_first_li: Caller-dependent routine to compute length of first interval
+ * @sk:		   Used by @calc_first_li in caller-specific way (subtyping)
+ * Updates I_mean and returns 1 if a new interval has in fact been added to @lh.
+ */
+int tfrc_lh_interval_add(struct tfrc_loss_hist *lh, struct tfrc_rx_hist *rh,
+			 u32 (*calc_first_li)(struct sock *), struct sock *sk)
+{
+	struct tfrc_loss_interval *cur = tfrc_lh_peek(lh), *new;
 
-		/* new loss event detected */
-		/* calculate last interval length */
-		seq_temp = dccp_delta_seqno(head->dccplih_seqno, seq_loss);
-		entry = dccp_li_hist_entry_new(GFP_ATOMIC);
+	if (cur != NULL && !tfrc_lh_is_new_loss(cur, tfrc_rx_hist_loss_prev(rh)))
+		return 0;
 
-		if (entry == NULL) {
-			DCCP_BUG("out of memory - can not allocate entry");
-			return;
-		}
+	new = tfrc_lh_demand_next(lh);
+	if (unlikely(new == NULL)) {
+		DCCP_CRIT("Cannot allocate/add loss record.");
+		return 0;
+	}
 
-		list_add(&entry->dccplih_node, li_hist_list);
+	new->li_seqno	  = tfrc_rx_hist_loss_prev(rh)->tfrchrx_seqno;
+	new->li_ccval	  = tfrc_rx_hist_loss_prev(rh)->tfrchrx_ccval;
+	new->li_is_closed = 0;
 
-		tail = li_hist_list->prev;
-		list_del(tail);
-		kmem_cache_free(dccp_li_cachep, tail);
+	if (++lh->counter == 1)
+		lh->i_mean = new->li_length = (*calc_first_li)(sk);
+	else {
+		cur->li_length = dccp_delta_seqno(cur->li_seqno, new->li_seqno);
+		new->li_length = dccp_delta_seqno(new->li_seqno,
+				  tfrc_rx_hist_last_rcv(rh)->tfrchrx_seqno);
+		if (lh->counter > (2*LIH_SIZE))
+			lh->counter -= LIH_SIZE;
 
-		/* Create the newest interval */
-		entry->dccplih_seqno = seq_loss;
-		entry->dccplih_interval = seq_temp;
-		entry->dccplih_win_count = win_loss;
+		tfrc_lh_calc_i_mean(lh);
 	}
+	return 1;
 }
+EXPORT_SYMBOL_GPL(tfrc_lh_interval_add);
 
-EXPORT_SYMBOL_GPL(dccp_li_update_li);
-
-static __init int dccp_li_init(void)
+int __init tfrc_li_init(void)
 {
-	dccp_li_cachep = kmem_cache_create("dccp_li_hist",
-					   sizeof(struct dccp_li_hist_entry),
-					   0, SLAB_HWCACHE_ALIGN, NULL);
-	return dccp_li_cachep == NULL ? -ENOBUFS : 0;
+	tfrc_lh_slab = kmem_cache_create("tfrc_li_hist",
+					 sizeof(struct tfrc_loss_interval), 0,
+					 SLAB_HWCACHE_ALIGN, NULL);
+	return tfrc_lh_slab == NULL ? -ENOBUFS : 0;
 }
 
-static __exit void dccp_li_exit(void)
+void tfrc_li_exit(void)
 {
-	kmem_cache_destroy(dccp_li_cachep);
+	if (tfrc_lh_slab != NULL) {
+		kmem_cache_destroy(tfrc_lh_slab);
+		tfrc_lh_slab = NULL;
+	}
 }
-
-module_init(dccp_li_init);
-module_exit(dccp_li_exit);